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Accel. of eletron in Electric field.

  1. Sep 4, 2008 #1
    1. The problem statement, all variables and given/known data

    How strong an electric field is needed to accelerate electrons in a TV tube from rest to one-tenth the speed of light in a distance of 5.5

    2. Relevant equations

    I used uniform accel. forumla v^2=V_o_+2a(delta X)
    v=3e7 (1/10th speed of light)
    V_o_=Rest
    m=9.11e-31(mass of eletron)
    delta X= .055meters
    all to find (a)
    to find the Accelaration

    and a=q/m(E)


    3. The attempt at a solution

    I need to find E i believe I came up with
    a=2.72 m/s^2
    and E= 3.98e-41 wich was wrong...;/

    Thankyou
     
  2. jcsd
  3. Sep 4, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Redo that calculation. (Your equation is OK.)
     
  4. Sep 4, 2008 #3
    Ok I did it again and got 8.18e15 for my (a)
    Then I need to find (E) so I changed the formula around so its "a/(q/m)=E" and I got 1.19e-33 ...wrong again...
     
  5. Sep 4, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good.
    That formula, though oddly written (get that fraction out of the denominator), is perfectly OK. Redo the calculation.
     
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